1. Field of the Invention
The present invention relates to a light blue flat glass having a high visible light transmittance.
2. Discussion of Background
At lobby openings, etc. of hotels, museums, art galleries, office buildings, etc., a glass screen having a large area with a width of from 2 to 3 m and a height of at least 3 m is used in many cases for such reasons as to see outside scenery, to emphasize visual continuity to outside, to present an open atmosphere, etc.
In a suspension system for such a glass screen having a large area, glass stands (hereinafter referred to as glass ribs) are used. The glass ribs are disposed vertically to the glass screen, and thus, an end face of the glass rib is exposed inside of the room (or inside of the building) or outside of the room (or outside of the building).
Heretofore, for such a glass screen having a large area, a flat glass has been used which tends to have green color or a yellowish green color as the thickness increases, and the end face of the glass rib also used to exhibit such a color.
For the purpose of solving such a problem of coloration of the end face of a flat glass, a soda-lime-silica glass having CoO incorporated in an amount of from 0.1 to 1 ppm, has been proposed (JP-A-2000-143283).
If it is attempted to industrially produce a soda-lime-silica glass plate containing from 0.1 to 1 ppm of CoO in a large quantity, the following problem is likely to result. Namely, industrial production of a soda-lime-silica glass plate is usually carried out in a scale of a few hundreds tons/day, but it is not easy to uniformly mix and disperse a very small amount of a CoO material in the glass material so that the content will be at most 1 ppm.
Accordingly, in the industrial production, fluctuation of the CoO content in the glass tends to be substantial, whereby the above-mentioned problem of coloration may not sufficiently be solved.